The Coast Guard is responding to a report of a rig explosion and fire "and people in the water'' in the Gulf of Mexico south of Vermilion Bay, authorities said.

Coast Guard Petty Officer Casey Ranel said the rig is around 90 miles south of Vermilion Bay and that a helicopter earlier today reported that it was in fire "and that there was smoke and there were people in the water.''

In an interview with CNN, Coast Guard Petty Officer Bill Colclough said there were 13 people on the rig and that all were accounted for. Twelve of the workers are in immersion suits and one is injured, he said.

Immersion suits protect the wearer from hypothermia.

All 13 people abandoned the rig after the explosion and are accounted for, but have not yet been rescued from the Gulf, the Coast Guard said.

Colclough said the rig was not actively producing at the time of the incident, but is still on fire. The explosion was reported around 9:30 this morning.

The injured will be taken Terrebone General Medical Center in Houma.

Eight helicopters, two airplanes and four boats are en route from Coast Guard stations in New Orleans and Houston, Ranel said.

She said the rig, Vermilion Oil Rig 380 is owned by Mariner Energy, but that details were scarce.

Vermilion Oil Rig 380 is a gas and oil rig in 340 feet of water in South Timbalier Block 316, according to company records.

Vermillion 380 is likely a fixed, manned production platform. It's not a well being drilled for oil, like BP's Macondo well and it's not a floating rig like the Deepwater Horizon.

Lee Hunt, president of the International Association of Drilling Contractors, said these types of rigs are permanently in place, often with a pipeline or oil and gas and water separation facilities on board.

"It's more like a small offshore refining operation," he said.

According to its website, Mariner is among the largest lease holders on the continental shelf with interests in approximately 240 federal leases and more than 30 state blocks, at year-end 2009.

In deepwater, Mariner holds a working interest in more than 90 blocks. The company has participated in more than 35 deepwater projects, operating more than half of them.